21: Describing Motion

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2-1 Describing Motion

• 32 points

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2-1 Rough Outline

• Motion
• Motion and Position
• Frame of Reference
• Distance
• Displacement
• Speed
• Calculating Speed
• Motion with Constant Speed
• Changing Speed
• Velocity
• Motion of the Earths Crust/Moving Continents

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I. Motion

• In order to determine the position of an object,
  you must have a ____ ____.
• Reference point
• Relative to means relating to. For example,
  your book says that motion occurs when the
  position of the object changes relative to the
  reference point. This means that when the object
  moves in relation to the reference point, it has
  moved.

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Reference Point
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(No Transcript)
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Motion, continued

• Once you have a reference point, then you can
  create a _____ of ______.
• Frame reference
• Where is the reference point (always) in a graph
  in your Math class?
• The origin
• The measurement of how far you have moved is
  called the ______ you have traveled.
• distance

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What is the distance? Each block represents 1
meter.
9 meters
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Motion, continued

• Unlike distance, ______ only measures how far you
  are from the start, NOT how far you have
  traveled.
• Displacement
• Displacement not only tells you how far you are
  from the start, but it also tells you ______ you
  are relative to the start.
• where

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What is the displacement? Again, each block
represents a meter.
3 meters east (or right)
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Speed

• Speed is the measure of ____ ____ an object
  travels in a given _____.
• How far, the distance, etc.
• Time
• What is the formula for speed?
• S d/t
• Name some common SI measures of distance
• Meter, kilometer, centimeter, etc.
• Name some common SI measures of time
• Nanosecond, microsecond, millisecond, second,
  minute, hour, day, month, year, decade, century,
  millenium. . .

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Example, page 40

• Step One write the formula
• S d/t
• Step Two fill the in values from the problem
  A car traveling at a constant speed covers a
  distance of 750 m in 25 s. What is the cars
  speed?
• S 750m/25s
• Step Three Do the Math, remember your units!
• S 30 m/s

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Please do 1, page 40

• Step 1
• Step 2
• Step 3

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Please do 2, page 40

• Step 1
• Step 2
• Step 3

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Optional Problem

• An object is moving at 43 km/hr. The object
  covers a distance of 52,856 cm. Please calculate
  the time in seconds required to complete this
  movement. (HINT USE DIMENSIONAL ANALYSIS!)

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Motion, continued

• What do we call the motion of an object that
  never changes its speed?
• Constant speed
• Most of the time, though, our speed is changing.
• Please take a look at page 41, figure 3
• While we can calculate average speed by the
  formula s d/t, we need a speedometer (or the
  derivative in calculus) to calculate the speed at
  any one point, also known as _______ speed.
• instantaneous

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Graphing Motion

• We often use a distance-time graph to show
  changing motion over time.
• Well use the motion detector to examine the
  distance-time graph tomorrow.

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Velocity

• Velocity tells more information than speed does.
  Speed tells you how fast something is going, but
  velocity tells you how fast the object is going
  AND in what ______ it is moving.
• Direction
• Look at the example on the next slide. Are the
  objects going in a constant speed? How about
  constant velocity?

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• Speed?
• Different
• Velocity?
• Different

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• Speed?
• Same
• Velocity?
• Different

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• Speed? (in relation to each other)
• Same
• Velocity? (in relation to each other)
• Same

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• Speed?
• Different
• Velocity?
• Different

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Motion of the Earths Crust

• The theory of _____ _____ posits that the
  landmasses of the Earth have moved considerably
  over time.
• Plate tectonics
• The crust and the upper mantle of the Earth are
  together called the ______.
• Lithosphere
• The pieces of the lithosphere float on the
  puttylike layer below, known as the asthenosphere.